Components of a wind turbine like a generator or a gear require lubrication with a lubricant, for example a liquid lubricant such as oil, to reduce friction in a bearing of such components. The liquid lubricant will degenerate with increasing time in use, which means that the friction is not reduced in a sufficient manner. The degeneration of the liquid lubricant is caused by particles as a result of abrasion, high pressure and temperature or chemical impacts. Eventually, the liquid lubricant will totally loose its lubricating abilities.
Therefore, it is common to exchange the liquid lubricant in fixed intervals, e.g. every five years. This is done manually by technicians who have to arrive at the wind turbine and to enter the nacelle of the wind turbine. Depending on the position of the wind turbine, such manual oil changing may have high cost implications.